Military intervention in internal conflicts represents a recurrent practice in international history. This thesis provides a theoretical framework for the study of the political and sociological processes that lead political elites to militarily intervene in internal conflicts. Following the renewed interest in political elites both in Sociology and International Relations, the thesis draws on Elite Theory to address the dual nature of political elites as both domestic and international actors. In doing so, it develops a framework for the study of military intervention centred on political elites that overcomes the limits of existing contributions on the subject. In particular, the thesis highlights how interventionary policies are shaped by three overlapping causal antecedents: elites’ contending ideological claims; elites’ struggle for both domestic and international power; and the relationship established by the intervener’s elite with elite and counter- elite groups in the target state. The thesis tests the plausibility of the proposed framework by examining US decisions in three cases: US intervention in the Cuban War of Independence (1898-1902); US intervention in the Russian Civil War (1918- 1920); and US non-intervention in the Spanish Civil War (1936-1939). This analysis highlights three elements. First, ideological considerations set significant limits to US cooperation with leaders in the target country despite the strategic rationale for cooperation against common enemies. Second, the interplay between international and domestic political considerations represented a fundamental ‘push factor’, shaping the objectives US elites sought. Third, foreign elite groups played a crucial role in ‘pulling’ US interventions, both by representing local allies instrumental to Washington’s objectives and by directly accessing and influencing US decision-making processes. For the same reasons, the lack of these push and pull factors are key to explaining US non-intervention in the Spanish case. Overall, the thesis offers a twofold contribution to the study of military intervention. First, it explores how military intervention permits decision- makers to affect the ‘circulation of elites’ in both their own societies and in other societies. Second, it indicates how military intervention affects the international system by altering ideological homogeneity, international alliances and hierarchical relations between elites.